Can I snap to face during transformation in animation?
Maybe "Parent" Helps.

First select the eyes, then the head with your Shift down to make a multi-select, hit Ctrl+P (Parent) and select "Object (Keep Transform)", then the head will be the parent of the eyes, the eyes will be the children of the head. The eyes will follow the head's transformation.

But I'd recommend you to apply rotation &amp; scales before you do it. Check if the scale properties of the objects are set to "1.0" by poping up properties with hotkey "N". If not "1.0", then press Ctrl+A and hit "Rotation &amp; Scales" to apply the both to the objects. That's because the rotation &amp; scale you've made haven't been consequently applied to the object before you confirm your application.

For more info, check this out: https://docs.blender.org/manual/en/latest/editors/3dview/object/properties/relations/parents.html